1. Field of the Invention
The present invention relates to a method of producing primarily gasoline and fuel gas when processing coal in the presence of superheated steam and fluidized sand. Carbon deposited on the sand is removed by oxidation to provide heat for coal conversion and carbon monoxide for regeneration of a metal reagent hydrogen generator. In the hydrogen generator, which preferably comprises a fixed bed of iron-chromium alloy, carbon monoxide produced by removal of carbon from the sand is passed up through the bed reducing the alloy to the active metal/metallic form and steam is thereafter passed downwardly through the bed to form hydrogen for use in the coal reactor. Distillate diesel oil separated from the coal reactor overhead may be hydrogenated and used for coal extraction prior to recycling along with coal to the coal reactor. A variety of process schemes downstream of the coal reactor may be utilized to remove sulfur, carbon dioxide and coal ash and to recover and/or recycle selected fractions of hydrocarbons from the coal reactor overhead product.
2. Description of the Prior Art
In the prior art the conversion of coal to marketable fuels has generally required substantial purchased or onsite oxygen often costing as much as the coal being processed. Also in the coal conversion processes of the prior art, carbon dioxide formation generally accompanied hydrogen production necessitating expensive carbon dioxide removal procedures. Moreover, where hydrogen production was generated by the interaction of iron and steam according to the Messerchmidt process and others, generally the iron had a tendency to to sinter and agglomerate decreasing the surface area of the iron and, therefore, drastically reducing the activity thereof.
The present invention provides for the use of a bed of iron and chromium alloy for hydrogen generation in order to ameliorate the problem of agglomeration. Also, in accordance with the present invention, the foregoing mode of hydrogen production is integrated with a coal reaction utilizing an admixture of sand and an iron and chromium alloy in order to remove and utilize carbon from the coal reactor to intermittently regenerate the bed of alloy and to provide heat for sustaining the coal conversion process.